1. Field of the Invention
The present invention relates generally to a sandblaster system. More specifically, the invention relates to a pollution free blaster system which prevents pollution due to dust, mine dust and so forth generated during blasting operation. The present invention also relates to a blaster head useful in the blaster system.
2. Description of the Background Art
Sandblasters are useful in removing weathered surface of concrete constructions, such as buildings and so forth, and rust on steel constructions, such as bridges, ships, gas tanks and so forth. On the other hand, Such sandblasters necessarily generate dust, mine dust and so forth and thus create pollution, during sandblasting operations. Therefore, in many cases, relatively large scale operations, such as covering the portion of the construction with a large sheet or tent, are required to prevent the dust, mine dust and so forth, from being a source of pollution.
In order to avoid such necessity, there has been proposed a wall blaster in U.S. Pat. No. 4,149,345, issued on April 17, 1979, to Iwao ATSUCHI. The wall blaster which is disclosed, comprises a plurality of sand injection nozzles so disposed as to be directed toward an opening of a sandblaster housing facing a surface to be treated for injecting working sand or other abrasive agent toward the surface to be treated, a working sand collecting chamber provided at the lower portion of the sandblaster housing for collecting the working sand injected from the injection nozzles and deflected from the surface to be treated, a plurality of compressed air injection tubes so disposed in the vicinity of the base of the respective injection nozzles as to direct the head of the tube toward the base of the nozzle and also to an open end of a sand house communicating with the collecting chamber in the vicinity there of for taking up the sand in the collecting chamber by means of an ejecting action of a high speed jet air flow injected therefrom and for reinjecting the sand from the injection nozzles to circulate the sand in the housing, upper and lower wheels provided at the front surface of the housing and a permanent magnet disposed at the front surface of the housing wherein the housing is arranged adjacent to the hull surface to be treated so as to be moveable along the hull surface while injecting the working sand from the injection nozzle.
For a similar purpose, the Japanese Utility Model First Publication (Jikkai) Showa 59-193657, published on Dec. 22, 1984 discloses a sandblasting device which has a sandblasting nozzle housed within a collecting hood. The sandblasting nozzle is connected to a feed hose through which the working sand or abrasive is fed via pressurized air and is designed for injecting working sand or other abrasive toward the surface to be treated. A collecting hood is connected to a collecting hose to collect the injected working sand or abrasive. The feed hose extends coaxially with the collecting hose. In the disclosed sandblasting device, the working sand or abrasive injected from the blasting nozzle is collected by means of the collecting hood and recirculated through the collecting hose.
Such sandblasters of the prior art are effective in preventing some of the dust, mine dust or so forth generated during the blasting operation from being discharged into the atmosphere. However, they do not yet completely prevent pollution from occurring during sandblasting operation.